Lamp socket

ABSTRACT

Lamp sockets formed to have plastic bodies are provided for automotive applications. The principal plastic bodies are molded to receive and hold plastic bulb inserts which are sized to fit standard bayonet light bulbs. Spring contacts, to make connections to the light bulbs, are inserted in the principal plastic bodies and are held in place by tangs which contact molded areas of the plastic bodies. Other tangs provide connections from the spring contacts through windows in spade terminals connecting to a wiring harness. Ground connections are provided by ground contact straps embodying tangs and other elements which secure them to the principal plastic body. The ground contact straps permit completion of a ground connection through another tang to the wiring harness or, alternatively, through a ground tab to a metal wall.

United States Patent 1191 Burgess et al. v

[ LAMP SOCKET [75] Inventors: James Patton Burgess, Brighton; Melvin W. Polkinghorn, Livonia; Stephen J. Brzozowski, Detroit, all of Mich.

[73] Assignee: International Telephone and Telegraph Corporation, New York, NY.

[22] Filed: 'June 28, 1972 [21] Appl. No.: 267,130

52 US. 01 339/14 R, 339/61 1,, 339/176 L, 339/217 s 51 Int. Cl ..n01r 3/06 [56] References Cited 7 UNITED STATES PATENTS 2,982,939 5/1961 Kirk 339/128 3,383,637 5/1968 Delano... 339/14 3,601,778 8/1971 Hollett 339/188 Mar. 26, 1974 Primary Examiner-Bobby R. Gay Assistant Examiner-Robert A. Hafer Attorney, Agent, or Firm.lames B. Raden; Delbert P. Warner ABSTRACT Lamp sockets formed to have plastic bodies are provided for automotive applications. The principal plastic bodies are molded to receive and hold plastic bulb inserts which are sized to fit standard bayonet light bulbs. Spring contacts, to make connections to the light bulbs, are inserted in the principal plastic bodies and are held in place by tangs which contact molded areas of the plastic bodies. Other tangs provide connections from the spring contacts through windows in spade terminals connecting to a wiring harness. Ground connections are provided by ground contact straps embodying tangs and other elements which secure them to the principal plastic body. The ground contact straps permit completion of a ground connection through another tang to the wiring harness or, alternatively, through a ground tab to a metal wall.

10 Claims, 8 Drawing Figures PMENFEWms new FIG. 1

LAMP SOCKET CROSS REFERENCES TO RELATED APPLICATIONS A related patent application now Pat. No. 3,718,892, directed to a Lamp Socket, Ser. No. 861,113 was filed on Sept. 29, 1969, in the names of James P. Burgess and Melvin W. Polkinghorn. Another related patent application now U.S. Pat. No. 3,668,603 for a lamp socket entitled Twist Lock Socket With Connector, Ser. No. 68,995 was filed Sept. 2, 1970 in the names of James P. Burgess, Melvin W. Polkinghorn and Steve .I. Brzozowski.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lamp sockets of particular utility with automotive vehicles. It relates especially to economical plastic lamp sockets for use in sheltered places when the need for weather-proofing is minimal. Lamp sockets according to the invention embody improved connectors of use in establishing stress relieving connections to wiring harnesses and simple connections to ground. The sockets are adaptable to permit plastic inserts for a wide range of socket bases regardless of depth and focal length. Connectors are provided which enable ground connections to be completed either to a wiring harness or to metal walls throughwhich the sockets have been placed.

2. Description of the Prior Art Until fairly recently, prior art automotive lamp sockets in use have consisted usually of a metal shell, an insulator and a spring through which the harness has been threaded. With these prior art devices, bulb contact terminals were staked onto the wires completing the socket-to-harness assembly. This has been a very costly assembly procedure which has been attended by other high costs due to the need to mount these metal sockets into the lamp housing. These metallic sockets have had a relatively low resistance to corrosion which often has resulted in.a short life and the need for costly replacements.

One method of mounting the metal sockets into the housing was by ,swedging or pressing the metal shell into the lamp housing. Another method was to have metal prong ring fingers on the socket which could be forced into the lamp housing. The bending rates of these fingers was extremely difficult to control and resulted in improper assemblies, high insertion efforts, and in general, was expensive.

Among the prior art devices are lamp sockets such as those disclosed in the'prior applications referenced above. These prior art sockets have overcome many of the objections to the use of metal sockets. They relate to a class of lamp sockets which provide weather-proof construction adaptable to use in areas exposed to outside weather, moisture and the like. This provision of weather-proof construction is necessary where sockets are placed in exposed positions but imposes costly penalties where sockets are to be located in protected places such as automobile trunks and covered weatherproof lamp housings.

out in the foregoing, objects of the present invention include the provision of new lamp sockets for installation in protected places where moisture seal is not required and the provision of novel grounding facilities while preserving all other important functions of the prior art devices.

The new sockets are adaptable to be connected directly to wiring harnesses through connectors which enable connections between the sockets and the wiring harness to be completed by pushing the components together. The connectors include elements which latch together to prevent the wiring harness from separating from the socket by simple pulling action. The latching elements may be characterized as snap-together connectors incorporating tangs which in cooperation with other elements latch the elementstogether, preventing the connector parts from being pulled apart after they have latched and provide relief for stresses between the connectors and the wiring harness leads.

The new sockets are formed to incorporate lampreceiving inserts which permit adaptation to all socket bases regardless of depth and focal length. A selfgrounding snap-in tab may be provided to eliminate the need for a separate ground wire when the sockets are mounted on a metallic housing.

The sockets include elements which mate with open ings in reflector elements permitting simple insertion and a quick twist to lock them in position in the manner disclosed in the above referenced patent applications.

BRIEF DESCRIPTION OF THE DRAWINGS The above mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional view illustrating the principal components of the present invention,

FIG. 2 is an enlarged view of the area in which a blade terminal and a spring contact meet,

FIG. 3 shows details of construction ofa blade terminal,

FIG. 4 illustrates, in section, certain salient relationships between a spring contact and the socket body,

FIG. 5 shows the relationship between a ground extension tab, the cutting edge of the tab and a rubber pad,

FIG. 6 illustrates in cross section various relationships between a ground strap, a ground extension tab and the walls of the socket body and of the bulb insert unit,

FIG. 7 shows further relationships between the ground contact strap, the ground extension tab, and the tang formed on the ground extension tab, and

FIG. 8 shows in greater detail the manner in which the boss and the tang of the ground extension tab engage the ground contact strap and the socket body, respectively.

DESCRIPTION OF A PREFERRED EMBODIMENT Turning first to FIG. 1, there is disclosed a sectional view which illustrates many of the most important aspects of a lamp socket in accordance with the present invention.

In FIG. 1, the lower socket body is indicated at 15. A bulb insert unit 16 is shown in position within the open end of the lower socket body 15. The bulb insert 'unit 16 is held in position by action between its own plastic extensions indicated as the plastic projections 10 and extensions in the form of lips 9 of the lower socket body. A spring contact 17 is shown positioned to establish contact between the blade terminal, or spade terminal, 21 of a wiring harness and a contact on the base of a standard bayonet base light bulb (not shown)v The elastic properties of a suitable rubber or plastic pad 20 may be used to help hold the socket against a thin wall.

The lamp receiving bulb insert unit 16 may be of one size to fit standard lamp bases. The plastic insert is not intended to be removed once it is inserted. As indicated in the drawings and the foreging description, the present invention makes use of a two-piece socket, the base and the plastic insert, instead of the one piece socket common in the past.

FIGS. 2 through 8 provide enlarged views of various elements and assemblies from FIG. 1. These Figures augment FIG. 1 to make it easier to understand both the mode of use and the assembly of sockets in accordance with the invention.

The first step in the assembly of a socket is to insert the proper number of spring contacts 17 into the lower socket body 15 so that the tang T1 on the spring contact (FIG. 4) becomes engaged under the lip 8 of plastic in the lower socket body and the tang T3 becomes engaged in an opening 5 against the wall 6 of the lower plastic body. The tang T1 prevents the spring from being pushed out or dislodged during the application of the blade terminal 21 as the socket is mated with a wiring harness. The tang T2 serves to provide strain relief against a pull by the blade terminal 21 and prevents the spring from being pulled through the spade or blade terminal receiving opening.

The next step is to insert the ground contact strap 18 (see FIG. 6) into the lower socket body. The ground contact strap incorporates a tang T4 which snaps under a lip of plastic at 30 to prevent the accidental release of the ground during insertion of a blade terminal. A tang T5 in the ground contact strap is formed to latch to a blade terminal which provides a connection to ground through the wiring cable, when such a connection is needed.

Next, the plastic bulb insert 16 is snapped into place so that the plastic projections 10 on the insert lockingly engage the lips 9 of the socket body thus perventing the insert from being disengaged.

Now the rubber pad 20 is slipped over the socket body to rest on the flange and is forced under the locating towers 31, 32 of the socket body so that the rubber pad will not come off during handling.

Finally, if ground is to be established to a metal housing, an L-shaped ground extension tab 19 is put in place with the sharp cutting edge 14 (see FIG. 6) left exposed over the rubber pad so as to make contact to the conductive housing. The other end of the tab 19 is pushed into the slot of the socket body until the tang T12 has been engaged under the lip 12. Meanwhile, the boss 13 on the ground extension tab has been forced into contact with the ground strap 18 so that a continuous electrical path may be made from the ground terminal of the lamp bulb in the bulb insert area through the ground strap to the ground extension tab and onto the conductive housing itself. The sharp cutting edge of the ground extension tab 14 acts as a paint striker under a high force condition when the socket is inserted into an electrically conductive housing so that a good contact is assured when the twist lock socket is turned into proper position on the housing.

The socket described herein is designed so that only the socket body need be tooled especially for each focal length. A common bulb insert is designed to fit all of these lower socket bodies for any specific focal length. Since there are two sets of bulb inserts, differing only in the location of the slots for the bayonets of the lamp bulb base, both of these bulb inserts will also fit into any socket body. This allows for maximum flexibility in utilization of the mold tooling of the socket components.

Once assembled, the socket mates with a blade terminal 21 having a hole, or window, 1 (FIG. 3) which engages the tang T2 of the spring contact 17 (FIG. 2) so that the terminal cannot be removed without depressing the spring contact. The terminal is prevented from going into the socket body 15 beyond a given distance by the shoulder 3. It will be noted that the window 1 in the spade, or blade, terminal is rectangular. The window slides readily over the tang T2 being guided by sidewalls of the terminal cavity to close confinement. This is in contrast to the use previously of a pin terminal which ruptured a membrane and held the terminal by means of its lance against removal. A bent nail-like tool may be used to remove the terminal by reaching through the window to depress the tang.

The blade terminal has a very low force insertion terminal because the spring contact has only a short distance to move to allow the blade to enter the socket yet a positive force is maintained by the spring against the blade as contained by the plastic wall of the plastic,

Earlier use of a picture frame type terminal was confined to connector applications where terminals were engaged with plastic fingers which require complicated mold tooling and are difficult to maintain uniformly in production.

Lastly, the spring contact utilizes a second tang T3 (FIG. 4), a cavity 5 in the socket body and a ledge 6 in a unique way to prevent the terminal from allowing the lower end of the spring from being distorted when the terminal and wire are pulled away from the socket body. As the spring starts to be deformed, the tang T3 engages the wall 6 of the cavity 5 anchoring the spring in place until the forces required for further distortion greatly exceed the required minimums of the automotive industry.

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

We claim:

1. A lamp socket structure for mounting through a mating opening in a thin walled housing, comprising a bulb insert unit formed of insulating material,

said bulb insert unit including means adapted to resaid socket body including lip means to engage said projection and tolock said bulb insert unit and said socket body together, and means, including a spring contact engageable in said socket body, to complete an electrical connection between a light bulb and a wiring harness, said spring contact including a plurality of fastening elements for engaging said socket body and elements of said wiring harness. 2. A lamp socket structure as claimed in claim 1, in which the bulb insert unit is substantially cylindrical in form and includes a projection forming a ground strap retaining element and in which a ground contact strap is engaged with said ground strap retaining element. 3. A lamp socket structure as claimed in claim 1, in which the bulb insert unit is substantially cylindrical in form and includes a projection forming a ground strap retaining element to retain one end of a ground contact strap, the socket body has a substantially cylindrical interior in said open end, and a slot extends along the cylindrical portion of said socket body to receive one end of said ground contact strap and support it under said ground strap retaining element. 4. A'lamp socket structure as claimed in claim 1, in which the bulb insert unit includes'means for receiving the retaining prongs of a bayonet base lamp bulb, and

said bulb insert unit, in cooperation with said spring contact, serves to retain said bulb in retaining grooves within said bulb insert unit.

5. A lamp socket structure as claimed in claim 1, in

which the socket body includes a groove and a lip for engaging fastening elements of said spring contact and retaining it within the socket body.

6. A lamp socket as claimed in claim I, in which a ground contact strap is fitted between the bulb insert unit and the socket body.

7. A lamp socket as claimed in claim 1, in which a ground contact strap is fitted between the bulb insert unit and the socket body, and

a ground extension tab is fitted between the socket body and the ground contact strap to provide a means for establishing a ground connection to a thin metal wall.

8. A lamp socket as claimed in claim 7, in which the ground extension tab includes a sharp edge to engage the thin metal wall and provide a ground contact therewith.

9. A lamp socket as claimed in claim 1, in which one of the fastening elements for the spring contact is a tang to engage a recess in said socket body and relieve tension on said spring contact.

10. A lamp socket as claimed in claim 1, in which the means to complete an electrical connection between a light bulb and a wiring harness includes a tang on said spring contact and a spade terminal connected to said wiring harness,

, said spade terminal including a window to engage said tang and provide a direct metallic connection from the spring contact, via the tang and the window, to the wiring harness. 

1. A lamp socket structure for mounting through a mating opening in a thin walled housing, comprising a bulb insert unit formed of insulating material, said bulb insert unit including means adapted to receive the base of a light bulb, said bulb insert unit including fastening means in the form of a projection, a socket body formed of insulating material, said socket body having an open end to mate with said bulb insert unit, said socket body including lip means to engage said projection and to lock said bulb insert unit and said socket body together, and means, including a spring contact engageable in said socket body, to complete an electrical connection between a light bulb and a wiring harness, said spring contact including a plurality of fastening elements for engaging said socket body and elements of said wiring harness.
 2. A lamp socket structure as claimed in claim 1, in which the bulb insert unit is substantially cylindrical in form and includes a projection forming a ground strap retaining element and in which a ground contact strap is engaged with said ground strap retaining element.
 3. A lamp socket structure as claimed in claim 1, in which the bulb insert unit is substantially cylindrical in form and includes a projection forming a ground strap retaining element to retain one end of a ground contact strap, the socket body has a substantially cylindrical interior in said open end, and a slot extends along the cylindrical portion of said socket body to receive one end of said ground contact strap and support it under said ground strap retaining element.
 4. A lamp socket structure as claimed in claim 1, in which the bulb insert unit includes means for receiving the retaining prongs of a bayonet base lamp bulb, and said bulb insert unit, in cooperation with said spring contact, serves to retain said bulb in retaining grooves within said bulb insert unit.
 5. A lamp socket structure as claimed in claim 1, in which the socket body includes a groove and a lip for engaging fastening elements of said spring contact and retaining it within the socket body.
 6. A lamp socket as claimed in claim 1, in which a ground contact strap is fitted between the bulb insert unit and the socket body.
 7. A lamp socket as claimed in claim 1, in which a ground contact strap is fitted between the bulb insert unit and the socket body, and a ground extension tab is fitted between the socket body and the ground contact strap to provide a means for establishing a ground connection to a thin metal wall.
 8. A lamp socket as claimed in claim 7, in which the ground extension tab includes a sharp edge to engage the thin metal wall and provide a ground contact therewith.
 9. A lamp socket as claimed in claim 1, in which one of the fastening elements for the spring contact is a tang to engage a recess in said socket body and relieve tension on said spring contact.
 10. A lamp socket as claimed in claim 1, in which the means to complete an electrical connection between a light bulb and a wiring harness includes a tang on said spring contact and a spade terminal connected to said wiring harness, said spade terminal including a window to engage said tang and provide a direct metallic connection from the spring contact, via the tang and the window, to the wiring harness. 